Two Simple 24-Hour Timer Circuit Schematics


Posted on Feb 6, 2014

These two circuits are multi-range timers offering periods of up to 24 hours and beyond. They can be used as repeating timers - or as single-shot timers. Both circuits are essentially the same. The main difference between them is their behaviour in single-shot mode. In single-shot mode - when the preset time has elapsed - Version 1 energizes the r


Two Simple 24-Hour Timer Circuit Schematics
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elay and Version 2 de-energizes the relay. The first uses less power while the timer is running - and the second uses less power after the timer has stopped. Pick the one that best suits your application. The Cmos 4060 is a 14-bit binary counter. However - only ten of those bits are connected to output pins. The remaining bits - Q1, Q2, Q3 and Q11 - do exist. You just can`t reach them. By adjusting R4 you can alter the frequency of the oscillator. So you can control the speed at which the count progresses. In other words - you can decide how long it will take for any given output pin to go high. If you want to use the timer in repeating mode - simply leave out D1. The count will carry on indefinitely. And the output pin will continue to switch the transistor on and off - at the same regular time intervals. Using "Trial and Error" to set a long time period would be very tedious. A better solution is to use the Setup tables provided - and calculate the time required for Pin 7 to go high. The Setup tables on both schematics are interchangeable. They`re just two different ways of expressing the same equation. For example, if you want a period of 9 Hours - the Range table shows that you can use the output at Pin 2. You need Pin 2 to go high after 9 x 60 x 60 = 32 400 seconds. The Setup table tells you to divide this by 512 - giving about 63 seconds. Adjust R4 so that the Yellow LED lights 63 seconds after power is applied. This...




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